Exam 4 Flashcards
Actual tissue damage/injury that impairs host function
disease
microbial parasite that causes disease, or tissue damage in host
pathogen
the ability of a parasite to inflict damage on the host- measured in virulence (differs from host-to-host)
pathogenicity
what pathogen is on
fomite
how does the bacteria adhere and infect the cells?
-exposure to fomite
-bacteria/virus adheres to cell
-invasion (virulence factors allow virus to infect)
-multiply and colonize; start producing toxins and enzyme that cause illness
-no toxins unless population is large enough (quorum sensing)
-adhesin- glyco- lypoprotein molecule on outer part of cell allows for adhesion to our cells(usually epithelial cells first)
Capsules
-part of adhesion(sticky, helps to stick to cell/eachother to form biofilms)
–not all have capsules
-thick slime layer on cell
-known as a virulence factor- help bacteria evade immune response
ex. of bacteria that have capsules:
Strep. pneumoniae
Frederick Griffith
-proved that the capsule was the virulence factor
-discovered transformation
What else do bacteria use for adherence?
fimbrae, pili, and flagella
-fimbrae- med.
-pili- short, hair like
-flagella (motility) but also help adhere
Dental caries (strep sobrinus and strep mutans)
-saliva= defense mechanism (lysozomes), wash out bacteria, prevent adhesion
-some bacteria use saliva to adhere
-strep sobrinus attaches to mucus and saliva
-strep mutans (attach to teeth and gums)
-once mouth is colonized, lactic acid fermentation, use sucrose that is eaten as nutrient source.
-glycolysis then lactic acid fermentation, causes plaque that decay teeth
invasiveness
ability to grow
tropism
ability for bacteria to target certain tissue
-strep pneumonia tropism is lungs; swallow=dies, inhale=invasion
bacteremia
bacteria is in blood but not actually colonizing blood; no replication. no replication, no colonizing, no producing toxins
septicemia
bacteria colonizing blood, reproducing, producing toxins
septic shock and death
virulence
ability to cause disease
virulence factors
anything that give bacteria/virus advantage (capsules, toxins, enzymes, etc.)
-many have several factors
What is LD-50?
measures virulence factors
-# of pathogens required to kill 50% of the animals in test group
-lower #= worse (doesn’t take a lot to kill population)
-high virulence- certain flu strains, ebola, strep pneumoniae
attenuation
-where bacteria/virus loses its virulence factor
-kept in lab for long time- no need for bacteria to produce virulence factors= becomes attenuated
How is attenuation beneficial?
used in vaccines.
-use attenuated strain, body forms immune response
-put into chicken eggs, colonize, extracted for vaccine- live attenuated vaccine- we produce memory cells- immune respones= works the best but can be dangerous for immune deficient ppl- get sick or can revert back to virulence
-some attenuated use dead virus
What is a compromised host? What kinds of people are compromised?
-don’t have good immune response= opportunistic pathogens, get very sick
-HIV/AIDS pts, cancer pts, elderly, ppl who take a lot of antibiotics
-get nosocomial infections (healthcare associated infections) like MRSA, C. Dif.
Tissue-destroying enzymes
-virulence factors
-enzymes usually exoenzymes(sent out by bacteria)
Hyalurondase enzyme
-breaks down hyaluronic acid in skin/tissues
(strep, staph, and clostridia cause boils (pyogenese= “pus forming”
Collagenase enzyme
enzyme breaks down collagen
(clostridia perferengin- gangrene)
Coagulase enzyme
enzyme that makes blood clot (strep aureus, only pathogenic strains produce coagulase)
-once infected in skin, produces coagulase- forms clot around bacteria- use as a barrier from macrophages- localized in boils)
Streptokinase enzymes
-prevents blood from clotting, breaks down fibrin; immune response- clot in area to prevent bacteria from spreading- strep pyogenese
What is an exotoxin?
